Limiting oxidation: effect of purging headspace O2 in a bottle conditioned IPA

[Miraculix]

Yeah, I was thinking of starting a thread to see if anyone has hard data on exactly how much o2 yeast scavenges. It's obviously more than zero, but definitely not as much as the old thinking on it. It sure does seem to help shelf life to have some yeast activity once the bottle is sealed, though, so that's great

I think it uses all the available o2 within the liquid, until there is no food left.

The problem, from my point of view, is that the oxygen from the air in the bottle does not get into solution fast enough. There seems to be still plenty of oxygen left in the headspace in the bottle, after the yeast ran out of food and it looks like this then slowly gets dissolved in the beer, after the yeast ran out of food, and then slowly oxidises it.

 

[Die_Beerery]

I think it uses all the available o2 within the liquid, until there is no food left.

The problem, from my point of view, is that the oxygen from the air in the bottle does not get into solution fast enough. There seems to be still plenty of oxygen left in the headspace in the bottle, after the yeast ran out of food and it looks like this then slowly gets dissolved in the beer, after the yeast ran out of food, and then slowly oxidises it.

O2 diffusion into liquid is nearly instant, and it can do 1-2ppm/hr easily. So if you have yeast that is dormant, the oxidation happens before it can absorb it. This is exactly why purging the headspace is better.
In a perfect scenario, you would prime in the fermenter, allow activity to pick back up. Then bottle, purge headspace, and cap.
Platinum standard:
Then take those bottles and place them in an empty keg, and purge that.
Why an empty keg? Because the caps leak, and due to partial pressure laws, you will have a gas exchange, thus oxygen entering the bottle though that. If in a purged keg you will be echaning with purge gas instead of o2. However the keg will also be doing diffusion though its gaskets, so ther eis that to deal with as well. But it's much slower than nothing.

 

[ncbrewer]

-If you don't have a beergun and CO2, the best alternative to limit oxidation is to bottle with almost no headspace.

Do you have any information about how much headspace is needed for safety? It seems like any reduction in headspace would increase the pressure (assuming no change in priming sugar) since there is less volume for the gas. I've tried reducing the headspace to about 3/4" and haven't noticed higher pressure - but that's a pretty crude way to judge pressure.

 

[Taket_al_Tauro]

In a perfect scenario, you would prime in the fermenter, allow activity to pick back up. Then bottle, purge headspace, and cap.

I do not prime in the fermenter, but I usually add a little bit of sugar solution at dry-hopping time. Then dry hop for 4-5 days at 60ish in my basement. No cold crash, and I'll move the fermenters up in my living room the evening before bottling. That way the beer will be typically between 65-70 F at bottling time. So I believe (o at least, I hope) to have enough active yeast in there during the transferring and bottling process.

I have been really happy with my bottle conditioned hoppy beers since following this process, plus the headspace purging step. But it is still difficult for me to know how much all of this really contributed to overall beer quality...because I have been tweaking other process steps at the same time, like water chemistry, hopping rates,... .

Platinum standard:
Then take those bottles and place them in an empty keg, and purge that.
Why an empty keg? Because the caps leak, and due to partial pressure laws, you will have a gas exchange, thus oxygen entering the bottle though that. If in a purged keg you will be echaning with purge gas instead of o2. However the keg will also be doing diffusion though its gaskets, so ther eis that to deal with as well. But it's much slower than nothing.

Are you serious about this?...Or do you know people actually doing this? This seems to me the last frontier of being anal ;-)

 

[doug293cz]

Do you have any information about how much headspace is needed for safety? It seems like any reduction in headspace would increase the pressure (assuming no change in priming sugar) since there is less volume for the gas. I've tried reducing the headspace to about 3/4" and haven't noticed higher pressure - but that's a pretty crude way to judge pressure.

Changing headspace won't change pressure in the headspace much, unless you increase the headspace by more than about 2X. With less headspace, less CO2 will come out of the beer during carbonation, keeping the headspace pressure in a reasonable range. This can all be calculated. If anyone is really interested, I can do a couple of sample calcs for the audience, but be careful what you wish for - it will get very mathy and geeky.

Brew on

 

[Gnomebrewer]

In a perfect scenario, you would prime in the fermenter, allow activity to pick back up. Then bottle, purge headspace, and cap.

Or prime with fresh krausen beer.

 

[ryanm8]

I've been bottling my heavily hopped NEIPA's for years with no color degradation, even months after. The tips here are pretty spot on.

- Bottle directly from fermenter with a bottling wand
- Batch prime in fermenter, wait 15-30 minutes for yeast to wake up before bottling
- Purge bottle before adding beer, and after if you have headspace.

One tip I'll add that hasn't been mentioned is to use plastic bottles if you can (preferably oxygen barrier bottles). The great thing about plastic bottles is you can squeeze them and cap with the beer having virtually no headspace. And the plastic can hold so much pressure you don't need to worry about the bottle breaking.

 

[doug293cz]

I've been bottling my heavily hopped NEIPA's for years with no color degradation, even months after. The tips here are pretty spot on.

- Bottle directly from fermenter with a bottling wand
- Batch prime in fermenter, wait 15-30 minutes for yeast to wake up before bottling
- Purge bottle before adding beer, and after if you have headspace.

One tip I'll add that hasn't been mentioned is to use plastic bottles if you can (preferably oxygen barrier bottles). The great thing about plastic bottles is you can squeeze them and cap with the beer having virtually no headspace. And the plastic can hold so much pressure you don't need to worry about the bottle breaking.

Plastic bottles, that have been squeezed, will create headspace when CO2 generation starts.

Brew on

 

[Bilsch]

Do you have any information about how much headspace is needed for safety? It seems like any reduction in headspace would increase the pressure (assuming no change in priming sugar) since there is less volume for the gas. I've tried reducing the headspace to about 3/4" and haven't noticed higher pressure - but that's a pretty crude way to judge pressure.

I do 1/4" or slightly less all the time and have had zero issues.

 

[Bilsch]

Are you serious about this?...Or do you know people actually doing this? This seems to me the last frontier of being anal ;-)

Yes he is serious and there are people doing this especially if your going to send beers to several competitions and want it the same over time.

 

[ryanm8]

Yep, they do. And like you said, it's CO2 headspace so nothing to worry about.

Plastic bottles, that have been squeezed, will create headspace when CO2 generation starts.

Brew on

 

[Taket_al_Tauro]

Yes he is serious and there are people doing this especially if your going to send beers to several competitions and want it the same over time.

Ok, for competitions I can see that it might make sense to take such extreme measures. Are people also sending the keg?

I've been bottling my heavily hopped NEIPA's for years with no color degradation, even months after. The tips here are pretty spot on.

- Bottle directly from fermenter with a bottling wand
- Batch prime in fermenter, wait 15-30 minutes for yeast to wake up before bottling
- Purge bottle before adding beer, and after if you have headspace.

One tip I'll add that hasn't been mentioned is to use plastic bottles if you can (preferably oxygen barrier bottles). The great thing about plastic bottles is you can squeeze them and cap with the beer having virtually no headspace. And the plastic can hold so much pressure you don't need to worry about the bottle breaking.

How are you dealing with dry hop matter when bottling this way?
I assume you do not cold crash, right?
Do you bag the dry hops?

Regarding plastic bottles, I do not have any experience myself, but I read that PET/plastic is more permeable to O2 than glass and that it will let some O2 in over time.

 

[Miraculix]

O2 diffusion into liquid is nearly instant, and it can do 1-2ppm/hr easily.

Too broad of a statement. It's depending on surface area etc.

Just based on visual inspection, the oxidation with unpurged headspace seems to start when the yeast starts to ran out of sugar and cannot use more oxygen for the metabolism. So it looks like there is still oxygen in the headspace which then slowly dissolves.

Another hint is that it was mentioned somewhere, I think by op, that splashing during bottling doesn't seem to have much of an impact on the oxidation, compared to the purge of the head space.

 

[Taket_al_Tauro]

Too broad of a statement. It's depending on surface area etc.

Just based on visual inspection, the oxidation with unpurged headspace seems to start when the yeast starts to ran out of sugar and cannot use more oxygen for the metabolism. So it looks like there is still oxygen in the headspace which then slowly dissolves.

Another hint is that it was mentioned somewhere, I think by op, that splashing during bottling doesn't seem to have much of an impact on the oxidation, compared to the purge of the head space.

I think the fact that O2 can diffuse rapidly into beer does not exclude that there will still be O2 in the headspace even weeks or months after. It seems very unlogical to me that all O2 in the headspace would jump into the beer within hours.

Regarding the splashing and then capping on foam, it's true it was like the headspace purged one...but I only did it so far with one bottle of a moderately dry hopped beer.
I would like to repeat that with a really heavily hopped beer ( like NEIPA).

 

[Die_Beerery]

Too broad of a statement. It's depending on surface area etc.

Just based on visual inspection, the oxidation with unpurged headspace seems to start when the yeast starts to ran out of sugar and cannot use more oxygen for the metabolism. So it looks like there is still oxygen in the headspace which then slowly dissolves.

Another hint is that it was mentioned somewhere, I think by op, that splashing during bottling doesn't seem to have much of an impact on the oxidation, compared to the purge of the head space.

Too broad how so?

How many of you folks have DO meters, and measure things like this?

I have 12, that I use to measure in my brewery.

 

[Taket_al_Tauro]

How many of you folks have DO meters, and measure things like this?

I have 12, that I use to measure in my brewery.

Then you must be the one who is able to provide hard data on how much O2 active yeast is really able to scavenge (at the end of fermentation, during dry hopping, during bottle conditioning, and so on...), as asked by @tyrub42
a few posts back. I would also be really interested to know more about this...

 

[Die_Beerery]

I already did.

http://www.********************/brewing-methods/deoxygenation-revisited/ is a yeast study

and here is another yeast/oxygen study

http://www.********************/brewing-methods/wort-study-1/

 

[Taket_al_Tauro]

I already did.

http://www.********************/brewing-methods/deoxygenation-revisited/ is a yeast study

and here is another yeast/oxygen study

http://www.********************/brewing-methods/wort-study-1/

Great, thanks for this!
I'll read your reports in more detail when I have some more time, but just by quickly browsing over them, it seems yeast is extremely powerful indeed in scavenging O2...
Heck... just 20 grams of sugar and some yeast (and not even some yeast nutrients?) in 10 gallons of pure water and you had it take DO down to zero in just 20 mins?....
That is really conforting for my poor-man, low tech approaches (no kegging, no closed transfers and so on...)

 

[Dusan Kovacevic]

I will read those studies in detail over the weekend but I would suspect that yeast will not savage much of the oxygen, especially if you are not adding fresh yeast for bottling.
The main, and most misunderstood, reason for that is the fact that yeast DO NOT use oxygen for fermentation. Fermentation is anaerobic metabolism pathway.
Yeast can also use aerobic metabolism pathway, which is called respiration, but tend not to do so as long as concentration of sugar in liquid is more than 0.4% which almost always is in beer. (it should be noted that yeast can use both pathways simultaneously but even when they do respiration is negligible)
Yeast, however, do use oxygen but only to produce sterols and fatty acids which are important for cell membrane strength and permeability.
In fact, yeast will use all available oxygen in less then an hour from pitching.

Now back to bottling beer and yeast scavenging oxygen.

By the time we bottle out beer yeast already went through fermentation process and are old and tired (especially if they were in fermenter for longer time and/or with high alcohol percentage beer)
By the bottling time yeast have produced all sterols and fatty acids that it needs.
If the above is incorrect we would not have to purge the head space as yeast would scavenge all the oxygen in the meter of minutes as they do when you pitch them in to the fermenter.
And to be clear we are talking about saccharomyces c. here, as other yeast, like Brett yeast for example, would have different properties and could not live without oxygen.

 

[Taket_al_Tauro]

If the above is incorrect we would not have to purge the head space as yeast would scavenge all the oxygen in the meter of minutes as they do when you pitch them in to the fermenter.

But the O2 in the headspace first needs to get inside the beer for the yeast to be able to pick it up... and the beer won't pick up the entirety of the headspace O2 within minutes.

The situation in the fermenter at the beginning of fermentation is quite diffrent compared to a sealed bottle. Nearly all of the O2 in the fermenter headspace will get pushed out through the airlock by the vast amounts of CO2 being produced during fermentation.
In a sealed bottle, the O2 cannot get pushed out. It is trapped there, and it will probably continue diffusing in the beer over weeks/months.

 

[ryanm8]

I dry hop with a 5 gallon BIAB bag so it allows plenty of room for extraction (it floats on the entire top of the beer). Do not use a small bag as you will lose significant flavor/aroma (I've tried that too). I used to toss the hops in loose, but all that did was increase hop burn and particulate vs. using a large bag.

I still get some of the very fine hop particulate into the bottles when doing it that way, but it's easy to just leave that at the bottom of the bottle along with the yeast when pouring into a glass. You could probably cold crash if you really wanted to leave all that behind (I might try that next time).

And yes plastic is more permeable to O2, but I think that really has more of an impact when you're talking about long term aging, which you won't do with an IPA. The longest I've went in a plastic bottle so far with a NEIPA was 3 months and it did not have any color degradation at all. And that was without oxygen barrier plastic bottles. So I would not be too concerned with the permeability.

Ok, for competitions I can see that it might make sense to take such extreme measures. Are people also sending the keg?



How are you dealing with dry hop matter when bottling this way?
I assume you do not cold crash, right?
Do you bag the dry hops?

Regarding plastic bottles, I do not have any experience myself, but I read that PET/plastic is more permeable to O2 than glass and that it will let some O2 in over time.

 

[Dusan Kovacevic]

Great, thanks for this!
I'll read your reports in more detail when I have some more time, but just by quickly browsing over them, it seems yeast is extremely powerful indeed in scavenging O2...
Heck... just 20 grams of sugar and some yeast (and not even some yeast nutrients?) in 10 gallons of pure water and you had it take DO down to zero in just 20 mins?....
That is really conforting for my poor-man, low tech approaches (no kegging, no closed transfers and so on...)

I already did.

http://www.********************/brewing-methods/deoxygenation-revisited/ is a yeast study

and here is another yeast/oxygen study

http://www.********************/brewing-methods/wort-study-1/

I actually had to read those straight away .
First of all, great work you have done there, your knowledge and equipment is obviously more advanced than anything most of us have here.
And, of course, your studies confirm that yeast will use all oxygen available very fast to synthesize what it needs.
But.
In both studies you are testing how fast will all oxygen be consumed by fresh yeast in water or fresh wort. Meaning you have healthy yeast that are ready to start producing sterols and fatty acids and propagate and then start fermenting.

What we have at bottling time is yeast that has already build their membranes, reach their maximum population in the medium, went through stress of fermentation and major temperature swings(if cold crashing). So yeast that already have build their membrane, are not as ready to propagate, are stressed and have been sitting in alcohol for a couple of weeks.
I suspect that those yeast will consume very little oxygen that will go into the beer form the head space.

It would be amazing if you would measure this and make another study to see how much oxygen, if any, yeast will consume in the bottle.
Hope you are going to do that, it would be an amazing read.

 

[VikeMan]

But the O2 in the headspace first needs to get inside the beer for the yeast to be able to pick it up... and the beer won't pick up the entirety of the headspace O2 within minutes.

There will always be some O2 in the headspace that doesn't get into the beer. It's because O2 (like any gas) will seek equilibrium between the beer and the headspace. But, the O2 in the headspace will ultimately get very low, because as the free O2 in the beer is used up in staling reactions, the balance is tipped, causing more O2 to enter the beer.

The above is a little bit simplistic, because in reality, O2 is moving back and forth between the beer and the headspace all the time. But the net movement is always toward equilibrium.

 

[Dusan Kovacevic]

But the O2 in the headspace first needs to get inside the beer for the yeast to be able to pick it up... and the beer won't pick up the entirety of the headspace O2 within minutes.

The situation in the fermenter at the beginning of fermentation is quite diffrent compared to a sealed bottle. Nearly all of the O2 in the fermenter headspace will get pushed out through the airlock by the vast amounts of CO2 being produced during fermentation.
In a sealed bottle, the O2 cannot get pushed out. It is trapped there, and it will probably continue diffusing in the beer over weeks/months.

You are absolutely correct. I was referring to someone mentioning that it takes minutes for oxygen from head space to be absorbent in beer, which is of course incorrect.

But even if it was correct it wouldn't matter as yeast will not consume it.
So the situation we have is oxygen being slowly absorbed in beer from head space (thus gradual oxygenation and change in color over time) and yeast savaging very little if any of that oxygen.

My whole point is we should ignore the roll of yeast in minimizing DO in bottle conditioned beer and focus on the real problems.

 

[Taket_al_Tauro]

I dry hop with a 5 gallon BIAB bag so it allows plenty of room for extraction (it floats on the entire top of the beer). Do not use a small bag as you will lose significant flavor/aroma (I've tried that too). I used to toss the hops in loose, but all that did was increase hop burn and particulate vs. using a large bag.

Thanks for these details! Gives me some additional food for thought... I dry hop loose because I had the same experiences as you when using small bags (less flavor/aroma impact overall).
What I do now, is transferring through a 200 micrometer polypropylene filter bag that I place in the bottling bucket. In this way I can retain nearly all but the finest hop particulate. Has worked great for me, with no or very little hop burn even for the most heavily hopped IPAs. But of course, it involves an open transfer so more chances for oxidation... Although as you surely noticed by now, I'm a firm believer in the power of active yeast to scavenge O2, even post fermentation ;-).

Another question: Do you find the sugar solution is mixing in evenly by batch priming the fermenter? I guess you are not stirring or anything, as that would work against the original pupose of bottling directly from the fermenter...

 

[Taket_al_Tauro]

But even if it was correct it wouldn't matter as yeast will not consume it.
So the situation we have is oxygen being slowly absorbed in beer from head space (thus gradual oxygenation and change in color over time) and yeast savaging very little if any of that oxygen.

My whole point is we should ignore the roll of yeast in minimizing DO in bottle conditioned beer and focus on the real problems.

If yeast wasn't effective in scavenging O2 post-fermentation, I believe your non-purged bottle would have taken on a darker color much sooner...
I do not have any hard data of course, but I believe that yeast does indeed decrease DO significantly when active (i.e., it has something to eat and it is not too cold), but of course will stop doing so when it is forced to go dormant.

 

[Dusan Kovacevic]

If yeast wasn't effective in scavenging O2 post-fermentation, I believe your non-purged bottle would have taken on a darker color much sooner...
I do not have any hard data of course, but I believe that yeast does indeed decrease DO significantly when active (i.e., it has something to eat and it is not too cold), but of course will stop doing so when it is forced to go dormant.

I do not agree for the simple fact that it takes time for O2 from head space to be absorbed into the beer and then it takes time for beer to actually oxidase (that doesn't happen instantly I guess). In my non purged beer visual signs of oxidizing started to appear between 5th and 9th day. Or do you think absorption of oxygen and actual oxidation (enough to be visible) happens much sooner? I'm not being smart ass here I'm genuinely asking for your opinion.

For this discussion to continue to be meaningful can you please clarify do you think that yeast use O2 for fermentation? Or do you think yeast use O2 for membrane building? It is very important for this to be clear, I believe.

And finally, I'm not claiming that I know for a fact that yeast is not using O2 in significant amounts while bottle carbonating. I am just saying that from my perspective is very unlikely for the reasons already stated a few times in this thread, and those reasons are based in scientific evidence.

 

[Taket_al_Tauro]

I do not agree for the simple fact that it takes time for O2 from head space to be absorbed into the beer and then it takes time for beer to actually oxidase (that doesn't happen instantly I guess). In my non purged beer visual signs of oxidizing started to appear between 5th and 9th day. Or do you think absorption of oxygen and actual oxidation (enough to be visible) happens much sooner? I'm not being smart ass here I'm genuinely asking for your opinion.

For this discussion to continue to be meaningful can you please clarify do you think that yeast use O2 for fermentation? Or do you think yeast use O2 for membrane building? It is very important for this to be clear, I believe.

And finally, I'm not claiming that I know for a fact that yeast is not using O2 in significant amounts while bottle carbonating. I am just saying that from my perspective is very unlikely for the reasons already stated a few times in this thread, and those reasons are based in scientific evidence.

Have a look at this Brulosophy exbeeriment:
http://brulosophy.com/2018/03/12/th...oning-on-new-england-ipa-exbeeriment-results/

Let's not look at the main exbeeriment... it is not very cheerful for bottle conditioning folks like us ;-)

But at the end of the report they included a kind of side note where they left the two glasses of beer for several hours in the open air. After just 16 hours, the color of both beers was already noticeably darker. After 36 hours, even the initially beautiful and light yellow variant looked like a brown, oxidised mess. Granted, those beers were exposed to the open air, and not just to the tiny amount in a bottle headspace. But still, it shows that oxidation can happen real fast.

I have honestly no idea why yeast would still want to consume O2 (or not) post fermentation. Your points do make sense. But in biology, I believe that things are very seldom black and white. At the end of fermentation, yes, the yeast has already undergone multiplication, it is in fermentation mode, it is tired , and so on...so it will most probably be by far not as effective in picking up O2 as compared to when the bulk of it is multiplying like mad at the fermentation's onset. But there might still be some significant growth going on, and O2 consumption, albeit at a much lower rate?
I am wildly speculating here... do not have any hard science to back this up.

 

[Dusan Kovacevic]

Have a look at this Brulosophy exbeeriment:
http://brulosophy.com/2018/03/12/th...oning-on-new-england-ipa-exbeeriment-results/

Let's not look at the main exbeeriment... it is not very cheerful for bottle conditioning folks like us ;-)

But at the end of the report they included a kind of side note where they left the two glasses of beer for several hours in the open air. After just 16 hours, the color of both beers was already noticeably darker. After 36 hours, even the initially beautiful and light yellow variant looked like a brown, oxidised mess. Granted, those beers were exposed to the open air, and not just to the tiny amount in a bottle headspace. But still, it shows that oxidation can happen real fast.

I have honestly no idea why yeast would still want to consume O2 (or not) post fermentation. Your points do make sense. But in biology, I believe that things are very seldom black and white. At the end of fermentation, yes, the yeast has already undergone multiplication, it is in fermentation mode, it is tired , and so on...so it will most probably be by far not as effective in picking up O2 as compared to when the bulk of it is multiplying like mad at the fermentation's onset. But there might still be some significant growth going on, and O2 consumption, albeit at a much lower rate?
I am wildly speculating here... do not have any hard science to back this up.

Well I would tend to lean towards the explanation that open atmosphere is contributing to that and I know you would disagree, and that's fine. Of course I think my arguments are better but you think yours are, so we have to agree to disagree (what a ****ing cliche).

But, I have another point here.

Lets say, for the sake of argument, you are correct and I'm completely wrong and yeast play major role in reducing DO in bottle carbonated beer. Even if that was truth we would still try to help the yeast and devise ways to reduce DO even further (like you did with your original experiment).

What I'm saying here is that what yeast do or don't do is not a variable that we control. Yeast are going to scavenge O2 or not regardless of what we do or think.

I'm suggesting that we concentrate our efforts on trying to devise the ways of minimizing DO in bottled conditioned beer, and if yest can help us there great, if they can't at least we did everything else that could be done.

All that being said I would still suggest everyone look up metabolic pathways of saccharomyces c. and what role O2 plays in their life. Think what you want but please have as much scientific facts as possible before you make your up mind.

 

[ryanm8]

Try dry hopping in a large bag and see if you notice any difference in flavor/aroma. I would think filtering in the bottling bucket could introduce some O2 at the start of the transfer. Once the bag is submerged, it should be OK though.

For batch priming, I tried not mixing the sugar solution and got uneven carbonation (although maybe if you wait long enough it will eventually mix). So I do stir, very carefully and slow to avoid any splashing. I still think there is an advantage to not transferring because you avoid the splashing that occurs when the transfer starts.

I think people overblow the rate at which beer can absorb oxygen. As long as you don't have splashing or bubbles, the beer is absorbing oxygen at a very slow rate. Once you introduce those variables then it's another story. So I focus on minimizing the splashing/bubbles as much as possible and that has worked for me.

One other note about yeast scavenging oxygen in the bottle: The more sugar I use when priming, the more yeast I find in the bottle. So looks like they are indeed multiplying, which would indicate they are scavenging oxygen as well.

Thanks for these details! Gives me some additional food for thought... I dry hop loose because I had the same experiences as you when using small bags (less flavor/aroma impact overall).
What I do now, is transferring through a 200 micrometer polypropylene filter bag that I place in the bottling bucket. In this way I can retain nearly all but the finest hop particulate. Has worked great for me, with no or very little hop burn even for the most heavily hopped IPAs. But of course, it involves an open transfer so more chances for oxidation... Although as you surely noticed by now, I'm a firm believer in the power of active yeast to scavenge O2, even post fermentation ;-).

Another question: Do you find the sugar solution is mixing in evenly by batch priming the fermenter? I guess you are not stirring or anything, as that would work against the original pupose of bottling directly from the fermenter...

 

[Bilsch]

When there is plenty of fermentable sugars present in the wort, yeast do prefer fermentation instead of respiration but in the deceleration and stationary phase they will use any available carbon source including respiring ethanol if oxygen is present. When bottle carbonating or bottling where there is yeast present, they are in competition with the antioxidants in the beer which is also quickly using up any available oxygen.

According to Hach, “in most beer, the majority of the oxygen is consumed over the period of one week, but the flavor doesn’t change for two to three months.” They here though are referring to filtered beer from which the yeast has been removed.

 

[Bilsch]

Here is more good information from Hach on TPO:

Package dO2 –
The easiest measurement to take on packaged beer is the dO2 of a package just off the filler without shaking the beer. It is important to measure as quickly as possible, so the product does not “consume” the oxygen in the beer. (Residual or live yeast may be hungry, plus oxidation by trace metals, etc.) In some packages there is a measurable difference within five minutes and in other packages the rate of oxygen consumption takes significantly longer, sometimes hours. It is always best to measure as quickly as possible.

https://tapintohach.com/2014/03/18/dissolved-oxygen-in-beer-how-it-compares-to-total-package-oxygen/

There is a lot of "I guess" and "I think" going on in this thread when a few minutes googling can give a lot of accurate information about this topic.

 

[Dusan Kovacevic]

When there is plenty of fermentable sugars present in the wort, yeast do prefer fermentation instead of respiration but in the deceleration and stationary phase they will use any available carbon source including respiring ethanol if oxygen is present. When bottle carbonating or bottling where there is yeast present, they are in competition with the antioxidants in the beer which is also quickly using up any available oxygen.

According to Hach, “in most beer, the majority of the oxygen is consumed over the period of one week, but the flavor doesn’t change for two to three months.” They here though are referring to filtered beer from which the yeast has been removed.

If your find yourself in stituation where there is less then 0.4% of sugar (when exatcly is that?) In the solution and plenty of O2 available you will, of course, have yeast switch to respiration and use ethanol and oxigen to produce energy (ATP).
But at that point oxygenation of beer is less of a problem as byproduct of ethanol respiration is VINEGAR.
There is no "guess" and "think" here. Biology is quite clear on this. Don't you think?

 

[Bilsch]

If your find yourself in stituation where there is less then 0.4% of sugar (when exatcly is that?) In the solution and plenty of O2 available you will, of course, have yeast switch to respiration and use ethanol and oxigen to produce energy (ATP).
But at that point oxygenation of beer is less of a problem as byproduct of ethanol respiration is VINEGAR.
There is no "guess" and "think" here. Biology is quite clear on this. Don't you think?

Yeast cells do not work in lock step, some may be fermenting while others are respiring especially as the formed glucose levels begin to drop because it is the glucose present that is inhibiting respiration. If this were not the case then open fermenting would produce horribly oxidized beers and we all know that is not true. Secondly yeast, at least beer yeast, very minor and not noticeable amount acetic acid as a byproduct of acetaldehyde when here is a lot of oxygen present. The main net reaction of respiration of glucose: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O. Maybe you are thinking of acetobacter?

And yes I agree with you the biology and science of this is quite clear, easy to find in the texts and all round the web. That is why I find it odd to read things like 'oxygen will stay in the headspace of the beer package' etc.

 

[Dusan Kovacevic]

Yeast cells do not work in lock step, some may be fermenting while others are respiring especially as the formed glucose levels begin to drop because it is the glucose present that is inhibiting respiration. If this were not the case then open fermenting would produce horribly oxidized beers and we all know that is not true. Secondly yeast, at least beer yeast, very minor and not noticeable amount acetic acid as a byproduct of acetaldehyde when here is a lot of oxygen present. The main net reaction of respiration of glucose: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O. Maybe you are thinking of acetobacter?

And yes I agree with you the biology and science of this is quite clear, easy to find in the texts and all round the web. That is why I find it odd to read things like 'oxygen will stay in the headspace of the beer package' etc.

I'm glad we agree on science part. So according to Crabtree effect yeast will not use respiration when there is more than 0.4% sugar in solution which is around 1.002 SG which is almost...well never.

 

[Bilsch]

I'm glad we agree on science part. So according to Crabtree effect yeast will not use respiration when there is more than 0.4% sugar in solution which is around 1.002 SG which is almost...well never.

That is 0.4% fermentable sugars (glucose, fructose, maltose, and sucrose) in the wort not total including unfermentable and more difficult to ferment sugars. So yes, as the ferment slows and these smaller molecule carbohydrates are gone, the Crabtree effect has little sway on which pathway to ATP the yeast take. As long as there is some activity, yeast will scavenge the oxygen in the headspace.

 

[tyrub42]

Here are the pics I mentioned earlier in the thread. Same exact beer, except one was fully purged (bottle and headspace) and one wasn't. Everything else was identical. The darker one wasn't as bad as you'd think by the color, but definitely had notes of oxidation and muted hop aroma. The lighter one went on to win the national homebrew comp in Taiwan in 2018. Neither one had Ascorbic Acid or metabisulfate, as I hadn't started experimenting with them at this time

 

[Dusan Kovacevic]

Here are the pics I mentioned earlier in the thread. Same exact beer, except one was fully purged (bottle and headspace) and one wasn't. Everything else was identical. The darker one wasn't as bad as you'd think by the color, but definitely had notes of oxidation and muted hop aroma. The lighter one went on to win the national homebrew comp in Taiwan in 2018. Neither one had Ascorbic Acid or metabisulfate, as I hadn't started experimenting with them at this time View attachment 676229 View attachment 676230

The difference is so obvious, great work you did there. How many days after the botleing is that?
And love your glasses mate

 

[Dusan Kovacevic]

That is 0.4% fermentable sugars (glucose, fructose, maltose, and sucrose) in the wort not total including unfermentable and more difficult to ferment sugars. So yes, as the ferment slows and these smaller molecule carbohydrates are gone, the Crabtree effect has little sway on which pathway to ATP the yeast take. As long as there is some activity, yeast will scavenge the oxygen in the headspace.

Ok, that's it then. You sloved the problem. There is no reason to do anything as yeast will eat up all the oxygen.
You can go on and bottle your NEIPAs and rely just on yeast to do the job.
I will try to think of other ways, thank you very much.
I just don't know how did you end up on this thread?

 

[tyrub42]

The difference is so obvious, great work you did there. How many days after the botleing is that?
And love your glasses mate

Thanks bro! These are Taihu Brewing's glasses. They're one of the most popular craft breweries in Taiwan and have amazing marketing and branding.

These were roughly 1 week after bottling. They were conditioned at an extremely sub-optimal 85ish degrees for 5-6 days. I live in a rooftop apartment in Taiwan so in the summer this was as cool as I could get them. Now I have a conditioning fridge so I'm able to condition at much better temps. The heat likely accelerated the color change but for the purposes of this experiment that's definitely a good thing. Cheers